Quantification of [ 99 Tc]TcO 4 - in urine by means of anion-exchange chromatography–aerosol desolvation nebulization–inductively coupled plasma–mass spectrometry

To sensitively determine 99 Tc, a new method for internal quantification of its most common and stable species, [ 99 Tc]Tc O_4^- , was developed. Anion-exchange chromatography (IC) was coupled to inductively coupled plasma–mass spectrometry (ICP-MS) and equipped with an aerosol desolvation system to provide enhanced detection power. Due to a lack of commercial Tc standards, an isotope dilution-like approach using a Ru spike and called isobaric dilution analysis (IBDA) was used for internal quantification of 99 Tc. This approach required knowledge of the sensitivities of 99 Ru and 99 Tc in ICP-MS. The latter was determined using an in-house prepared standard manufactured from decayed medical 99m Tc-generator eluates. This standard was cleaned and preconcentrated using extraction chromatography with TEVA resin and quantified via total reflection X-ray fluorescence (TXRF) analysis. IC coupled to ICP-MS enabled to separate, detect and quantify [ 99 Tc]Tc O_4^- as most stable Tc species in complex environments, which was demonstrated in a proof of concept. We quantified this species in untreated and undiluted raw urine collected from a patient, who previously underwent scintigraphy with a 99m Tc-tracer, and determined a concentration of 19.6 ± 0.5 ng L −1 . The developed method has a high utility to characterize a range of Tc-based radiopharmaceuticals, to determine concentrations, purity, and degradation products in complex samples without the need to assess activity parameters of 99(m) Tc. Graphical Abstract